In the field of automotive vehicles it has become popular to employ steering column assemblies that include tilt and telescoping functions, such assemblies being known also as “reach and rake steering column assemblies”. The use of motors to translate a steering wheel relative to a vehicle operator also has seen increased use.
During a vehicle collision, there are commonly two impacts. In a primary impact, the vehicle impacts another object. In a secondary impact, a vehicle occupant impacts a component of the vehicle. For example, a vehicle operator sometimes impacts the steering wheel due to inertia. In order to protect drivers from such secondary impacts, it has become common practice to use an impact-absorbing type steering column.
The structure of an impact-absorbing type steering column apparatus is such that when the driver suffers a secondary impact, the impact energy acts on the steering column in the frontward direction of the vehicle. The steering column may detach from one or more fixation points with the vehicle body and move forward (e.g., in a collapse stroke), so that the impact energy is absorbed in the course of the collapse stroke. An external collapsing column assembly is an example of a system in which the entire column will translate relative to its fixation points. An internal collapsing column assembly typically will be fixed at one or more fixation points near one of the ends of the assembly within the vehicle. During a collapse stroke from a secondary impact, components of the assembly will longitudinally collapse (e.g., generally within the volume it occupies within the vehicle in normal operation; that is, generally within its “footprint” in the vehicle), but generally will not collapse beyond a certain distance relative to a predetermined fixation point. An internal collapsing system thus has a stroke, but will remain fixed to the vehicle at the one or more fixation points.
For many applications, steering column assemblies incorporate both tilt and telescopic functions. For these, it is common to employ motors to perform each function. For example, one motor may be operated to actuate the steering column assembly generally in an upward or downward vertical direction to adjust the height of a steering wheel relative to an operator of the vehicle and thus perform the tilt function. Another motor may be operated to actuate the steering column assembly to adjust the fore/aft position of the steering wheel relative to the vehicle operator. The latter typically achieves the adjustment by way of translation of a telescopic tubing arrangement by which at least one tube associated with the steering wheel translates relative to a shaft for steering.
For improving upon existing collapsible steering column assemblies (and especially internal collapsing systems), as compared with typical existing systems, it is desired for an acceptable solution to include some or all advantages as compared with existing assemblies, such as reduced weight, reduced number of components, reduced “footprint”, a collapse stroke of at least about 70 mm (e.g., about 80 to 100 mm or more), or a structural platform that allows tunability and/or variability to allow the use of common parts to meet differing performance specifications for different vehicles, but otherwise requires minimal hardware substitution.
The following U.S. patent documents may be related to the present invention: U.S. Pat. Nos. 5,547,221; 5,890,362; 6,961,146, 6,264,239; 6,224,104; 5,477,744; 7,322,610; 7,350,816; 6,686,225; 7,410,190; and 7,258,366, all of which are incorporated by reference herein for all purposes. European application No. EP 1555188A1 also may have teachings related to the present invention and is incorporated by reference herein.